correctly support the image content format shape for sending images

Author: leafo

openai/init.lua

@@ -13,7 +13,9 @@ local content_format = types.string + types.array_of(types.one_of({
   }),
   types.shape({
     type = "image_url",
-    image_url = types.string
+    image_url = types.string + types.partial({
+      url = types.string
+    })
   })
 }))
 local test_message = types.one_of({

openai/init.moon

@@ -13,7 +13,9 @@ empty = (types.nil + types.literal(cjson.null))\describe "nullable"
 
 content_format = types.string + types.array_of types.one_of {
   types.shape { type: "text", text: types.string }
-  types.shape { type: "image_url", image_url: types.string }
+  types.shape { type: "image_url", image_url: types.string + types.partial {
+    url: types.string
+  }}
 }
 
 test_message = types.one_of {